Attach dough hook and turn mixer on to stir on low speed. Add in 220 g All-purpose flour, 30 g fine granulated sugar, ½ tsp salt, ½ tsp Instant yeast, 2 Tbsp. milk powder (20 g), and mix well.
Pour in 90 g water and 20 g egg, mix well until dough is formed, about 2 minutes on medium speed.
Add in 15 g butter, knead on medium speed for about 15 minutes or until the dough is smooth and elastic, the dough is able to stretch without breaking easily.
Cover and proof the dough for 45 minutes. Dough does not rise well in cold weather; place them in warm place such as oven with a cup of hot water if the surrounding temperature is cold.
Without donut cutter: Divide dough into 7 portions, roll into balls and flatten into circle, use a round cookie cutter or small measuring cup to cut a hole in the middle. With donut cutter: Roll out the dough with rolling pin and use donut cutter to cut out the shape. Place the donut dough on a piece of non-stick baking paper.
Cover and proof for 45-60 minutes. Place them at warm place, about 30°C if the weather is cold.
Heat oil to 150°C, gently drop donut into the oil, fry both sides until golden brown.
Preparing sugar glaze: Mix 50 g icing sugar, 10 g milk powder, ⅛ tsp salt and 2 ½ water, stir until no visible lumps. Place the melted icing sugar glaze in hot water bath, stir in 1 tsp of butter.
Coat with icing sugar glaze.